Ultrasensitive multiplex optical quantification of bacteria in large samples of biofluids

Efficient treatments in bacterial infections require the fast and accurate recognition of pathogens, with concentrations as low as one per milliliter in the case of septicemia. Detecting and quantifying bacteria in such low concentrations is challenging and typically demands cultures of large samples of blood (~1 milliliter) extending over 24-72 hours. This delay seriously compromises the health of patients. Here we demonstrate a fast microorganism optical detection system for the exhaustive identification and quantification of pathogens in volumes of biofluids with clinical relevance (~1 milliliter) in minutes. We drive each type of bacteria to accumulate antibody functionalized SERS-labelled silver nanoparticles. Particle aggregation on the bacteria membranes renders dense arrays of inter-particle gaps in which the Raman signal is exponentially amplified by several orders of magnitude relative to the dispersed particles. This enables a multiplex identification of the microorganisms through the molecule-specific spectral fingerprints

Surface-Enhanced Raman Scattering Holography

Nanometric probes based on surface-enhanced Raman scattering (SERS) are promising candidates for all-optical environmental, biological and technological sensing applications with intrinsic quantitative molecular specificity. However, the effectiveness of SERS probes depends on a delicate trade-off between particle size, stability and brightness that has so far hindered their wide application in SERS imaging methodologies. In this Article, we introduce holographic Raman microscopy, which allows single-shot three-dimensional single-particle localization. We validate our approach by simultaneously performing Fourier transform Raman spectroscopy of individual SERS nanoparticles and Raman holography, using shearing interferometry to extract both the phase and the amplitude of wide-field Raman images and ultimately localize and track single SERS nanoparticles inside living cells in three dimensions. Our results represent a step towards multiplexed single-shot three-dimensional concentration mapping in many different scenarios, including live cell and tissue interrogation and complex anti-counterfeiting applications.Peer ReviewedPostprint (author's final draft

Commissioning of the LHCb Silicon Tracker using data from the LHC injection tests

LHCb is a single-arm forward spectrometer dedicated to the study of the CP-violation and rare decays in the b-quark sector. An efficient and high precision tracking system is a key requirement of the experiment. The LHCb Silicon Tracker Project consists of two sub-detectors that make use of silicon micro-strip technology: the Tracker Turicensis located upstream of the spectrometer magnet and the Inner Tracker which covers the innermost part of the tracking stations after the magnet. In total an area of 12 m^2 is covered by silicon. In September 2008 and June 2009, injection tests from the SPS to the LHC were performed. Bunches of order 5x10^9 protons were dumped onto a beam stopper (TED) located upstream of LHCb. This produced a spray of ~10 GeV muons in the LHCb detector. Though the occupancy in this environment is relatively large, these TED runs have allowed a first space and time alignment of the tracking system. Results of these studies together and the overall detector performance obtained in the TED running will be discussed

Radiation Monitoring System for the LHCb Inner Tracker

The performance requirements and the design of the Radiation Monitoring System (RMS) for the LHCb Inner Tracker are presented. Details of the Metal Foil Detector technology employed for the RMS are described, along with results from tests of RMS prototypes

Measurements of the branching fractions of B+→ppK+ decays

The branching fractions of the decay B+ → pp̄K+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment. The total branching fraction, its charmless component Mpp̄ < 2.85 GeV/c2 and the branching fractions via the resonant cc̄ states η c(1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are [Equation not available: see fulltext.] Upper limits on the B + branching fractions into the η c(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained

Performance of the LHCb Silicon Tracker with first data

The LHCb Silicon Tracker consists of two sub-detectors the Tracker Turicensis and Inner Tracker that are constructed from silicon microstrip technology. Performance studies of both sub-detectors using data taken during the LHC synchronization tests are described

Production, Commissioning and First Data of the LHCb Silicon Tracker

We give here a short review of the LHCb Silicon Tracker, the main points of the module production and quality control, followed by the commissioning of the detector. Problems that were found during production or commissioning are described and the first performance assessment of the installed detector with “beam data” is given

The LHCb Silicon Tracker

The Silicon Tracker is a large-surface silicon micro-strip detector that covers the full acceptance of the experiment in a single tracking station upstream of the spectrometer magnet and the inner-most part of the three tracking stations downstream of the magnet. Special emphasis has been put on module quality assurance at all stages of the production. Various tests are performed after each production step and each module goes through several burn-in cycles. The design of the LHCb silicon detectors is described and the main lessons learnt from the R&D phase are summarized. Focus will be on the experience from module production and the quality assurance program

Observation of the decay Bc→J/ψK+K−π+B_c \rightarrow J/\psi K^+ K^- \pi^+

The decay $B_c\rightarrow J/\psi K^+ K^- \pi^+$ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb$^{-1}$. A signal yield of $78\pm14$ decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+ decays to that of $B_c \rightarrow J/\psi \pi^+$ decays is measured to be $0.53\pm 0.10\pm0.05$, where the first uncertainty is statistical and the second is systematic.Comment: 18 pages, 2 figure